1. Field of the Invention
The present invention relates to a data communication method using a plurality of communication lines. More particularly, the invention relates to a data communication method in which a plurality of communication stations each operable in transmitting and receiving modes are contained, and one communication station, when operating in a transmitting mode, divides data into a plurality of data blocks and sends the data blocks in parallel through a plurality of communication lines to the other communication station, while the other communication station, which receives the data blocks, operates in a receiving mode to receive the data blocks coming in through the plurality of communication lines and composes or synthesizes the data blocks into the original data.
2. Discussion of the Related Art
In a conventional data communication system, only one communication line is used for data communication between communication stations, for example, facsimile devices. Accordingly, the communication data is serially transmitted through one communication line. For this reason, much time is taken for the transmission of image data containing a great amount of information, such as image data of news paper or magazines.
However, in recent years, an integrated service digital network (ISDN) for handling digital information has been put into practical use. With the ISDN, a plurality of communication lines can be currently used for data communication.
The ISDN is a communication network in which the information output from various types of communication devices, such as telephones, facsimile devices, telexes, and the like, which are connected through a bus to a domestic service line terminal unit (DSU), are arranged into the information of a digital form, enabling parallel data communication among those devices through a plurality of communication lines.
With prevalence of the ISDN, a new communication system, called a super-high-speed communication system, has been proposed. In this communication system, communication data is divided into a plurality of data blocks, and those data blocks are transmitted in parallel through a plurality of communication lines.
Articles describing the super-high-speed communication system using a plurality of communication lines disclose general ideas of the communication system. However, any of those articles does not disclose the detailed techniques of the communication system.
To be more specific, when a transmitting station is sending block data to another station in a super-high-speed communication mode, if all of the communication lines are used by the currently progressing communication in the super-high or normal speed communication mode, viz., free communication lines are absent, the transmitting station cannot send another document data.